Lecture on 2018-4-5.pdf - (a Illustrate the micrbstructure...

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Unformatted text preview: (a) Illustrate the micrbstructure, label the phases and calculate the weight fraction of the OL phase that IS proeutectic in a 10 wt% Si- 90wt% Al alloy at 576°C (b) Illustrate the microstructure, lama and calculate the weight fraction of the [3 phase that 1s proeutectic in a 20 wt%Si-80 wt% Al alloy at 576°C. Atomic percentage. silicon 30 Weight percentage, silicon ustrate the mi __-- - m e, label the phases and calculate the amount of each phase present in 1kg of a 90 wt% Sn—lO wt% Pb solder alloy at 300°C, b 200 °C, 100°C, d d 0°C. (a) () (c) an 0 lfii/Wn Atomic percentage, tin ——O—-—_._ L 0C 10 20 30 40 50 60 70 80 90 400 - = ~:' 734' flpflwfigé C Kg Figures 9-16 ‘20 7’0” of each phase present 1n 1kg of 90 wt% Sn—lO wt% Pb solder alloy at (a) ,QQOS (b) 200 0c, (c) 1000 . g, / /0\( 5 /‘ 5 0‘ 07 : ,gLfi /$ : (é _ qpa‘ 351,; 75 79/ Atomic percentage, tin ma 5 , a. mom °C 10 20 3Q 40 50 60 70 80 90 r Weight percentage, tin 18 Figures 9-16 k A mixture of 3.0 pound tin (Sn) powder and 7.0 pound lead (Pb) powder is heated to 350 0C and a uniform melt is obtained. The melt is then slowly cooled down from 350 0C. (a) At what temperature will the melt begin to solidify and what is the Mn of the solid phase? ’NvOOZ/ (2 Wtz 5" (b) At what temperature will you have equal weight of li 'd and solid phase? What is the composition of the solid and the liquid phase? ' C 71% G (c) At what temperature will the melt completely solidify? What is the microstructure, and what are the phases at this temperature? \ 8/? [/ ' {1; )- profiled/‘2 I :1 Atomic percentage, tin 0/11” 644/20sz 0 Weight percentage, tin Figures 9-1 6 A mixture of 3.0 pound tin (Sn) powder and 7.0 pound lead (Pb) powder is heated to 350 OC and a uniform melt is obtained. The melt is then slowly cooled down from 350 0C. (a) Aljzdlallempera-Harewill the melt begin to solidify and what 18 the composition of the solid phase? 7350 C 22 I 2 W1? 9 YA (b) At what temperature will onu uhave equa weight of liquid and solid phase? hat IS the COM liquid phase? I?) wt“, "1:531 (c) At what temperature will the melt completely solidify. at is 3the microstrut e, nd what are the phases at this temperature? Atomic percentage, tin °C 40 50 60 70 90 400 300 40 “,7 50 60 70 80 90 Sn Weight percentage, tin Figures 9.16 Eutectoid Steel A steel with eutectoid composition is slowly cooled down from 1000°C to room temperature and a coarse pearlite microstructure is obtained. What will be the weight percentage of cementite in pearlite? What will be the weight percentage of ferrite in pearlit'e? Atomic percentage, carbon t" “- - E? ‘._ .1‘ . O 8 3 D 5' n G Refer to the following F e-F e3C phase diagram: (1) what is the eutectic temperature, eutectic composition and the eutectic reaction? (2) what is the eutectoid temperature, eutectoid composition and eutectoid reaction? (3) illustrate the three microstructures of a slowly cooled hypereutectoid steel of composition 1. l3wt% C at the locations A, B and C. moo.- ' I. ‘ I . I ,0 w Allllwwllllfl ‘llllllllllfl IJfilIllflflllllfl WWII-Illllllln “ lam-IIIIIIHWHII 500 ll- cementite __ =:55::”“==::=H 6 Weight percent carbons FesC 6 Quake-3 MM’tJ/F +04%“; 1”jg-m) Hypoeutectoid Steel 1kg 0.5 wt % C steel was slowly cooled down from 1100 0C to room temp. (a) Illustrate the microstructure at 800 0C, at 728 0C, and at room temp; (b) Calculate the amount of proeutectoid 0c phase at grain boundaries at room temp; (0) Calculate the total amount of 0t phase in the product at room temp. Atomic percentage, carbon °C 1 ,700 t I l 1100 0 oz of 0-77 11:: 800 . ‘ \J‘ a 700 .L:‘- "PM“ o- w mlfifillll ‘2 Urn/0‘01 500 i ‘ . _ mall-III Flgure 9 19 ’ 0.4/1 1 0.35 300 / I)": 200 W7 0F o \ ' e 8 {-5910 m — ,__—_ :/ :7 7D“ ’ 5.6?«0 m Eutectoid Steel A steel with eutectoid composition is slowly cooled down from 1000°C to room temperature and a coarse pearlite microstructure is obtained. What will be the weight percentage of cementite in pearlite? What will be the weight percentage of ferrite in pearlite? Atomic percentage, carbon °C 2 s 10 15 20 25 [III “I. I. l-----—-- Figure 9-19 Weight percentage, carbon 4 ...
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